BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Northern Harrier Population Trend in California

All statesGeneralists

Northern Harrier in California has fallen sharply: down 71% on the route-weighted index since 1970.

-71%Since 1970
113Routes In State
56Years

Notable Northern Harrier Trends in California

long arc declinecomputed index

Northern Harrier has fallen sharply in California: down 71% on the route-weighted index since 1970.

Northern Harrier Population Forecast in California

If the recent trend holds, Northern Harrier in California is projected to fall about 12% by 2029 — from 0.21 in 2024 to a central estimate of 0.19 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±122.8%, with 100% of held-out values landing inside the 95% band.

-12%Change by 2029
0.19Projected 2029 index
0.00–0.4695% range
±122.8%Backtest error
19682029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.210.000.48
20260.200.000.48
20270.200.000.47
20280.190.000.47
20290.190.000.46

Northern Harrier Survey Routes in California

Routes recording Northern Harrier in California.
Dorris820191972
Atwater720121971
Riovista620241968
Oilfields619991976
Athlone620071973
Collegeville520041968
Yreka520191973
Moreno419861968
Hollister420071974
Davis Creek419981980
Ora Loma420241972
Auburn319801970
Ingalls320001978
Cohasset319991974
Orland320111975
Ventucopa319991975
Brawley320091977
Tranquillity320041972
Hollister 2320212012
Big Pine219931982
Haiwee Res219971996
Palo Verde220212003
Lenwood219951975
Coachella Cn220002000
Lockwood Val219871987

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.